package com.study.demo.utils;

import lombok.extern.slf4j.Slf4j;

import java.text.*;
import java.util.Calendar;

@Slf4j
public class GenerateSequenceUtil {


    /** The FieldPosition. */

    private static final FieldPosition HELPER_POSITION = new FieldPosition(0);

    /** This Format for format the data to special format. */

    private final static Format dateFormat = new SimpleDateFormat("yyyyMMddHHmmssS");

    /** This Format for format the number to special format. */

    private final static NumberFormat numberFormat = new DecimalFormat("0000");

    /** This int is the sequence number ,the default value is 0. */

    private static int seq = 0;

    private static final int MAX = 9999;

    /**
     * 时间格式生成序列
     * @return String
     */

    public static synchronized String generateSequenceNo() {

        Calendar rightNow = Calendar.getInstance();

        StringBuffer sb = new StringBuffer();
        dateFormat.format(rightNow.getTime(), sb, HELPER_POSITION);

        numberFormat.format(seq, sb, HELPER_POSITION);

        if (seq == MAX) {
            seq = 0;
        } else {
            seq++;
        }

        log.info("THE SQUENCE IS :" + sb.toString());

        return sb.toString();

    }


    public static void main(String[] args) {

        System.out.println(generateSequenceNo());
    }

}
